Sandro,
Here's a little demo app for your code. It displays a random convex
polygon and the associated MER. Click on the display panel to
generate new polygons.
Michael
package jtsdemos.minimumenclosure;
import com.vividsolutions.jts.algorithm.ConvexHull;
import com.vividsolutions.jts.geom.Coordinate;
import com.vividsolutions.jts.geom.GeometryFactory;
import com.vividsolutions.jts.geom.Polygon;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.image.BufferedImage;
import java.util.Random;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
/**
* A simple app to demonstrate Sandro Zacchino's minimum enclosing
* rectangle (MER) code. It generates a random convex polygon, calculates the
* MER, and displays both on screen. Mouse click on the display panel to
* generate new polygons.
*
* @author Michael Bedward
*/
public class Demo {
private static final double CLOUD_MIN = 150;
private static final double CLOUD_W = 200;
private static final int IMGW = (int)(CLOUD_W + 2 * CLOUD_MIN);
private Polygon hullPoly;
private Polygon merPoly;
public static void main(String[] args) {
(new Demo()).doDemo();
}
private void doDemo() {
generatePolys();
final JPanel panel = new JPanel() {
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
BufferedImage bufImg = new BufferedImage(IMGW, IMGW,
BufferedImage.TYPE_INT_ARGB);
Graphics2D gr = (Graphics2D) bufImg.getGraphics();
gr.setColor(Color.BLUE);
Coordinate[] hullCoords = hullPoly.getCoordinates();
Coordinate c0 = hullCoords[0];
for (int i = 1; i < hullCoords.length; i++) {
gr.fillOval((int)c0.x-4, (int)c0.y-4, 9, 9);
Coordinate c1 = hullCoords[i];
gr.drawLine((int)c0.x, (int)c0.y, (int)c1.x, (int)c1.y);
c0 = c1;
}
gr.setColor(Color.MAGENTA);
Coordinate[] merCoords = merPoly.getCoordinates();
c0 = merCoords[0];
for (int i = 1; i < merCoords.length; i++) {
Coordinate c1 = merCoords[i];
gr.drawLine((int)c0.x, (int)c0.y, (int)c1.x, (int)c1.y);
c0 = c1;
}
((Graphics2D)g).drawImage(bufImg, null, 0, 0);
}
};
panel.addMouseListener(new MouseAdapter() {
@Override
public void mouseClicked(MouseEvent e) {
generatePolys();
panel.repaint();
}
});
panel.setToolTipText("click for new polygon");
final JFrame frame = new JFrame("MER demo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(panel);
frame.setSize(IMGW, IMGW);
SwingUtilities.invokeLater(new Runnable() {
public void run() {
frame.setVisible(true);
}
});
}
private void generatePolys() {
hullPoly = randomConvexPoly();
merPoly = MinimumEnclosure.computeMER(hullPoly);
}
private Polygon randomConvexPoly() {
Random rand = new Random();
final Coordinate[] cloud = new Coordinate[10];
for (int i = 0; i < cloud.length; i++) {
cloud[i] = new Coordinate(
CLOUD_MIN + CLOUD_W * rand.nextDouble(),
CLOUD_MIN + CLOUD_W * rand.nextDouble());
}
ConvexHull hull = new ConvexHull(cloud, new GeometryFactory());
return (Polygon) hull.getConvexHull();
}
}
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